Translation:Her eyes are so big, did she use the Meitu app?
I understand why he wrote it like that. Cause when we learn English, we are told to use the present perfect once the time in the past is not specified and the past event has an influence on the current situation. Seems like both of these conditions are fulfilled here.
That's not a correct definition of Present Perfect. Present Perfect is used to talk about the past in a general way, when the time is IRRELEVANT (not when it's not mentioned) and what matters is the EXPERIENCE itself. I can speak about a specific incident without mentioning the time and it will still be Past Simple. For example: "I spoke with my mother about my new job."
I had the same question. "是" has been used this way in at least one other Duolingo exercise.
My best guess is that this involves the grammar at https://resources.allsetlearning.com/chinese/grammar/Stating_the_effect_before_the_cause. If so, "是" is short for "是因為" ("it is because") with the "因為" part having been elided away.
This would mean that the second clause is literally: "Is (because) (she) used Meitu app?"
I never have thought like that. プリクラ stands for the Print Club. It is basically a photo printing machine. Young people, or especially girls, take a photo with their friends and share the photo among them at that very moment to record their friendship forever.
It seems that filtering functions were introduced a decade later in 2005. They called it サギプリ as a brunch of プリクラ, meaning a deceiving プリクラ. https://imidas.jp/ryuko/detail/N-05-1-504-05.html